Method and system for dynamic in-situ phosphor mixing and jetting

ABSTRACT

A system and method for depositing a phosphor composition onto a light emitting device improves manufacturing yield, simplifies conventional processes, and decreases costs. For example, a method of dispensing a phosphor composition onto a light emitting device includes dispensing a portion of the phosphor composition onto the light emitting device utilizing a plurality of colored phosphor dispensers each for dispensing a respective type of phosphor. Power is applied to the light emitting device to emit light, and a characteristic the light emitted by the light emitting device is detected. Phosphor mixing and phosphor dispensing are dynamically controlled. Therefore the color characteristics of phosphor dispensed on LEDs are consistent. The system and method may also reduce the difference between detected characteristic of the light and a desired characteristic of the light.

BACKGROUND

1. Field

The present disclosure relates to the manufacture of light emittingdevices, and more particularly, to the manufacture of broad-spectrumlight emitting diodes having a phosphor layer.

2. Background

Solid state devices, such as light emitting diodes (LED)s, areattractive candidates for replacing conventional light sources such asincandescent and fluorescent lamps. LEDs have substantially higher lightconversion efficiencies than incandescent lamps and longer lifetimesthan both types of conventional light sources. In addition, some typesof LEDs now have higher conversion efficiencies than fluorescent lightsources and still higher conversion efficiencies have been demonstratedin the laboratory. Finally, LEDs require lower voltages than fluorescentlamps, and therefore, provide various power saving benefits.

Unfortunately, LEDs produce light in a relatively narrow spectrum. Toreplace conventional lighting systems, LED-based sources that producewhite light are desired. One way to produce white light is to deposit aphosphor material on the LEDs, such that monochromatic light emittedfrom blue or UV LEDs is converted to broad-spectrum white light. Thephosphor material may be formed by mixing a phosphor powder into apolymer such as silicone at a pre-defined concentration, or with apre-defined recipe, resulting in a suspension of phosphor particles inthe silicone. This mixture is then deposited onto the LED at apre-defined volume and/or weight, and subsequently subjected to a curingprocedure. The resulting phosphor-coated LEDs are then tested and putinto different color bins according to the actual tested color. Variousprocesses for suspending phosphor particles in silicone carriers areknown in the art.

Using these processes, it is difficult to achieve consistent opticalproperties, such as color consistency. Often, due to the process ofsuspending the phosphor particles in the carrier, the uniformity oflight across large numbers of LEDs is difficult to maintain. Operatorerror may result in the wrong mixture, leading to an off-color failureof the whole lot. Further, the viscosity of the phosphor mixture maychange during deposition, or the phosphor suspension may settle at potlife, causing a wide range of color bins. Moreover, other factors suchas the chip wavelength, the phosphor profile, the substratereflectivity, etc., can also cause variation even when the dispensingvolume and weight are consistent. The above issues generally can not becaught in real-time, and thus, when they are discovered during testingit is too late to recover the parts and they must be scrapped. Themanufacturing process itself is often time consuming and costly,requiring multiple fabrication steps to complete. All of these issueslead to increased cost in manufacturing of broad-spectrum LEDs.

Accordingly, there is a need in the art for simplified and improvedprocesses for applying a phosphor material to LEDs and other solid statelighting devices.

SUMMARY

In various representative aspects, the present disclosure provides for amethod of dispensing a phosphor composition onto a light emittingdevice. According to an exemplary method, expected characteristics ofthe light, such as a correlated color temperature (CCT) and/or a set ofcoordinates in a color space (e.g., the CIE 1931 color space), and anexpected total dispensing volume or weight of the phosphor composition,are input into a controller. A first amount of the phosphor compositionis dispensed onto a surface of the light emitting device utilizing aplurality of jetting heads, the jetting heads including substantiallypure silicone jetting head for dispensing substantially pure siliconeand a plurality of colored phosphor jetting heads, each for dispensing arespectively colored phosphors.

After the first amount of the phosphor composition is dispensed, apulsed power is applied to the light emitting device, causing the lightemitting device to emit light, which is then detected with a lightdetector. Characteristics of the detected light are compared with theexpected characteristics, and if needed, the relative dispensing of thepure silicone and the at least one colored phosphor are adjusted to movethe detected characteristics toward the expected characteristics. Theprocess is repeated, and when the detected characteristic of the lightis within a predetermined range of the desired characteristic of thelight and also an amount of the phosphor composition on the surface ofthe light emitting device meets or exceeds the expected total dispensingvolume, dispensation of the phosphor composition ceases.

In some embodiments, a method of dispensing a phosphor composition ontoa light emitting device includes dispensing a portion of the phosphorcomposition onto the light emitting device. A characteristic the lightemitted by the light emitting device is detected, and relative amountsof respective portions of the phosphor composition are adjusted toreduce a difference between the detected characteristic of the light anda desired characteristic of the light.

In some embodiments, a system for dispensing a phosphor composition ontoa light emitting device includes a light sensor for detecting acharacteristic of light emitted from the light emitting device and aplurality of phosphor dispensers for dispensing a respective colorphosphor and pure silicone onto a surface of the light emitting device.The phosphor and the silicone dispensers are adapted to be controlled inresponse to the detected characteristic of the light emitted from thelight emitting device.

In some embodiments, a computer-readable medium stores a computerprogram which, when executed by a computer, causes the computer toperform a process for manufacturing a light emitting device. Thecomputer program includes code for dispensing a portion of the phosphorcomposition onto the light emitting device, code for detecting acharacteristic of light emitted by the light emitting device, and codefor adjusting relative amounts of respective portions of the phosphorcomposition to reduce a difference between the detected characteristicof the light and a desired characteristic of the light.

These and other aspects of the invention are more fully comprehendedupon review of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, together with the specification, illustrateexemplary embodiments of the present invention, and, together with thedescription, serve to explain the principles of the present invention.

FIG. 1 is a block diagram illustrating a system for dispensing aphosphor composition onto a light emitting device;

FIG. 2 is a flow chart illustrating a process for dispensing a phosphorcomposition onto a light emitting device; and

FIG. 3 is a color chart illustrating characteristics of light accordingto the CIE 1931 color space.

Elements and steps in the figures are illustrated for simplicity andclarity and have not necessarily been rendered according to anyparticular sequence. For example, steps that may be performedconcurrently or in different order are illustrated in the figures tohelp to improve the understanding of embodiments of the presentinvention.

DETAILED DESCRIPTION

In the following detailed description, only certain exemplaryembodiments of the present invention are shown and described, by way ofillustration. As those skilled in the art would recognize, the inventionmay be embodied in many different forms and should not be construed asbeing limited to the examples set forth herein. Also, in the context ofthe present disclosure, when an element is referred to as being “on” ordispensed “onto” another element, it can be directly on the otherelement or be indirectly on the other element with one or moreintervening elements interposed therebetween.

Certain aspects of the present invention may be described herein interms of functional block components and various processing steps. Suchfunctional blocks may be realized by any number of hardware or softwarecomponents configured to perform the specified functions and achieve thevarious results. For example, a controller is described for performingcertain calculations, making decisions, and providing control signals.Such a controller may be implemented in hardware and/or software, andthe functions described may be embodied in a computer-readable mediumthat stores a computer program which, when executed by a computer,causes the computer to perform the described functions.

In addition, the present invention may be practiced in conjunction withthe manufacture of any number of devices in addition to light emittingdevices, and the system described is merely one exemplary applicationfor the invention.

Further, the present invention may employ any number of conventionaltechniques for programming control points, sensing characteristics oflight, calculating and adjusting properties of a composition, and thelike.

Like reference numerals designate like elements throughout thespecification.

Conventional systems and methods for manufacturing light emittingdevices having a phosphor composition include pre-mixing a phosphorpowder in silicone to make the phosphor composition utilizing apredetermined recipe with an aim to achieve a broad-spectrum “white”light. That is, a typical LED produces light in a relatively narrowspectrum, while white light is frequently desired for lighting purposes.Thus, a conventional process typically includes predetermining a recipefor the phosphor composition based on knowledge of the properties of thephosphor constituents of the composition, knowledge of the spectrum ofradiation emitted by the LED, and other factors that may affect theemitted spectrum, with an aim for a complementary additive mixing of theemitted light from the excited phosphors and the LED to result in aperception of white light. This phosphor composition is then depositedon the LED at a predetermined volume and/or weight and cured, and theresulting phosphor-coated LEDs are then tested. Based on the spectrummeasured from each individual LED, the LEDs are generally placed intodifferent bins or categories, for example, separating the devices basedon the correlated color temperature (CCT) and/or a set of coordinates ina color space, such as a CIE color space.

Using these conventional processes, it is difficult to achieveconsistent optical properties. Often, due to the process of suspendingthe phosphor particles in the carrier, the uniformity of light acrossthe LEDs is difficult to maintain. Operator error may result in thewrong mixture, leading to an off-color failure of the whole lot.Further, the phosphor suspension may settle at pot life, or theviscosity of the phosphor mixture may change, causing a wide range ofcolor bins. Moreover, other factors such as the chip wavelength, thephosphor profile, the substrate reflectivity, etc. can also causevariation even when the dispensing volume and weight are consistent. Theabove issues generally can not be caught in real-time, and thus whenthey are discovered during testing it is too late to recover the partsand they must be scrapped.

A process according to an aspect of this disclosure avoids a number ofthese and other issues by utilizing feedback during the dispensation ofthe phosphor to dynamically control the relative amounts of the phosphorcomposition dispensed onto a light emitting device such as an LED.

Methods and systems for manufacturing a light emitting device mayoperate in conjunction with a production system 100. FIG. 1 illustratesa production system 100 according to an exemplary embodiment, includinga controller 110, a dispenser 120, a sensor 130, a power supply 140, anda light emitting device 150.

The controller 110 may be a microprocessor or other computer, aprogrammable gate array, an application specific circuit, or any othertype of controller with calculation, input, and output functions and acapability to execute stored instructions, perform predeterminedactions, etc.

The sensor 130 may be an optical sensor or other measurement sensorcapable of detecting one or more characteristics of light emitted by thelight emitting device 150, such as a correlated color temperature and/orcolor points (i.e., a set of coordinates in a color space). For example,the sensor 130 may be a charge coupled device (CCD), a colorimeter, orany other suitable sensor known to those skilled in the art. The sensor130 may include a combination of a sensing device and the controller110. The sensor 130 may include a fiber light guide for guiding lightfrom the light emitting device to the sensor. The sensor 130 may sendinformation, such as the one or more characteristics of the light, to aninput of the controller 110.

The dispenser 120 may be coupled to an output of the controller 110,such that the controller 110 provides a signal to the dispenser 120 tocontrol the dispenser 120. The dispenser may include one or more ofvarious silicone and phosphor dispensers, e.g., thermal jets,piezoelectric jets, continuous jets, squeeze tubes, syringes, and thelike, which may carry out a variety of functions. The dispenser 120 mayinclude one or more jetting dispensers for jetting droplets ofrespective colors of phosphor onto a surface of the light emittingdevice.

For example, in an exemplary embodiment, the dispenser 120 includes ayellow jetting dispenser for dispensing yellow phosphor, a green jettingdispenser for dispensing green phosphor, and a red jetting dispenser fordispensing red phosphor. In a further embodiment, the jetting dispensersfor dispensing the colored phosphors are configured to jet a highconcentration (e.g., a suspension of greater than 30 wt %, approximately50 wt %, or approximately 80 wt %) of their respective color phosphorpowder suspended in a substantially transparent medium such as silicone.

The dispenser 120 may further include a substantially pure siliconedispenser, e.g., a silicone jetting head, for dispensing substantiallytransparent or clear silicone onto the surface of the light emittingdevice, in conjunction with the colored phosphor dispensers. Thedispenser 120 may further include a plurality of reservoirs for storingthe concentrated phosphor suspensions and the transparent silicone inliquid form for later dispensation.

In some embodiments, each of the dispensers or heads (e.g., the jettingheads) of the dispenser 120 are configured to dispense droplets of puresilicone or high-concentration colored phosphors, respectively, atindividually variable and controllable rates and/or for individuallyvariable and controllable amounts of time to yield a phosphorcomposition, including the several colors of phosphor powder, the puresilicone, and, in some embodiments, other constituents. The jettingheads may dispense droplets with volumes ranging from 1 nanoliter tohundreds of milliliters, or may dispense respective portions of thephosphor composition as a constant stream. The dispensation of portionsof the pure silicone and various colors of concentrated phosphor may beoffset relative to each other in time, or may be at substantially thesame time. Further, the precise location that each of the dispensersactually dispenses its respective portion of the phosphor composition onthe surface of the light emitting device may be at the same or differentlocations from one another.

The dispenser 120 may be configured for jetting the phosphor compositionin at least a partial vacuum. In this way, the need for de-gassingand/or mixing of the phosphor composition after dispensation may bereduced or eliminated.

A system as described above reduces or eliminates the separateprocessing step of mixing the phosphor composition to a predeterminedratio of colored, powdered phosphors and silicone, as the respectivecolors and the silicone are “mixed” in situ as they are dispensed, forexample, on the surface of the light emitting device. Thus, the ratio ofthe components of the mixed phosphor composition may be preciselycontrolled and varied as the phosphor composition is dispensed.Furthermore, the ratio of the components of the mixed phosphorcomposition may be different from lot to lot, or even from device todevice, but as discussed above, because other factors besides thephosphor composition can affect the resultant light spectrum, thedevices and lots may have precisely controlled and uniform colorcharacteristics.

Furthermore, the above-described system enables the creation ofvariously layered or patterned phosphor structures on any surface,including a surface of a light emitting device.

The light emitting device 150, or the platform where the light emittingdevice 150 is located, may include a heating element 151. The heatingelement 151 enables the phosphor composition to be cured duringdispensation or closely thereafter, to reduce or eliminate issuesrelated to settling of the suspension of phosphor powder in thesilicone. Furthermore, the heating element enables control over theviscosity of the phosphor composition, for example, by heating thecomposition to reduce its viscosity and to enable the composition toflow more evenly and/or quickly over the surface of the light emittingdevice 150.

The power supply 140 may supply power to the light emitting device 150.The controller 110 may provide a control signal for controlling thepower supply 140, or the power supply 140 may operate independently ofthe controller 110. The power supply 140 may provide a voltage/currentto the light emitting device 150, the voltage/current being constant(DC), alternating (AC), or pulsed. In embodiments where the power supply140 provides a pulsed power, the pulses may be controlled in theiramplitude, their high and/or low peak voltage/current, their period,frequency, and/or their duty cycle. Further, the light emitting device150 may include one or a plurality of light emitting devices, and thepower supply 150 may provide power to the one or any number of theplurality of light emitting devices. In embodiments where the lightemitting device 150 includes a plurality of light emitting devices, thepower supply 150 may provide individually controllable power to one ormore (i.e., any subset up to and including all) of the plurality oflight emitting devices.

FIG. 2 is a flow diagram illustrating an exemplary process of dispensinga phosphor composition onto a light emitting device. The process may beperformed by circuitry, a network processor, a computer-controlleddispensing system with feedback, or by some other suitable means. Forexample, the process may be performed by the system of FIG. 1.

Referring together now to FIGS. 1 and 2, in block 210, a target lightcharacteristic may be inputted into the system. The inputting of thetarget light characteristic may be accomplished by an operator enteringone or more desired characteristics of light emitted by the lightemitting device into a user interface such as a keyboard or touch-screeninterface coupled to the controller 110. The target lightcharacteristics may be stored in memory such as a ROM, a magneticstorage, or an EEPROM, or in a volatile memory such as RAM. Someexamples of target light characteristics include a correlated colortemperature (CCT) and color coordinates (e.g., coordinates in a colorspace, such as CIE x and CIE y). The target light characteristic orcharacteristics entered in the system may further include a range,allowing for a tolerance of certain errors in meeting the targetcharacteristics of the light.

In block 220, a dispense ratio may be set. That is, the dispenser 120may include a plurality of dispense heads, some of which may be adaptedto dispense colored phosphors. In an exemplary embodiment, threedispense heads are adapted to dispense red, yellow, or green phosphor,respectively, wherein the red, yellow, or green phosphor may be a highconcentration (e.g., greater than about 30%) of phosphor powder in asuspension in a medium such as silicone. Here, a dispense ratiocorresponds to relative amounts of the different colors of phosphor. Forexample, a dispense ratio might be 2:2:1, that is, 2 parts red phosphorto 2 parts yellow phosphor to 1 part green phosphor.

The dispense ratio may further include a portion of the phosphorcomposition from a fourth dispense head in the dispenser 120, includinga transparent or clear medium such as silicone. That is, the dispenseratio in an exemplary embodiment may be 2:2:1:1, that is, 2 parts redphosphor to 2 parts yellow phosphor to 1 part green phosphor to 1 partsilicone. In some embodiments, the dispense ratio may be controllable tovery fine precision, and in some embodiments, a discrete and smallnumber of dispense ratios may be available.

On the other hand, a process according to various exemplary embodimentsmay forgo the initial setting of the dispense ratio in block 220. Thatis, in embodiments including feedback control and automatic correctionof the dispense ratio, to be discussed in further detail below, theinitialization of the dispense ratio may not be necessary. Thus, theinitial dispense ratio may be the same initial value each time theprocess is run, or the initial dispense ratio may be whatever ratio waslast utilized by the system, or, in some embodiments, the initialdispense ratio may be any value.

In block 230, a target amount of phosphor composition may be set. Thatis, the system may be provided with a predetermined amount (e.g., aweight or a volume) of the phosphor composition to be dispensed by thedispenser 120 onto one or a plurality of light emitting devices 150.This target amount may be utilized later in the process, as describedbelow, as one criterion for determining when to end the dispensation ofthe phosphor composition. The target amount may be pre-set at a factory,manually entered by an operator into the controller 110, or loaded froma communications interface coupled to the controller 110.

Skipping over block 290, to be described below, in block 240, thedispenser 120 may dispense a portion of the phosphor composition ontothe light emitting device 150. The amount of the phosphor compositionactually dispensed in a particular iteration of block 240 may becontrolled and limited to a predetermined amount, for example, apredetermined weight or a volume. The dispenser 120 may further includea heater and/or cooler for controlling the temperature, and thereforethe viscosity of the phosphor composition being dispensed onto the lightemitting device 150. This enables improved control of the amount beingdispensed in step 240.

Block 240 may include further sub-processes including positioning of thelight emitting device 150 and/or the dispensing heads in the dispenser120, baking and/or curing the light emitting device 150 by utilizing theheater 151 after dispensation of the phosphor composition, or waitingfor a period of time after dispensation. In various embodiments thatinclude a heater 151 and a heating sub-process, rapidly curing thephosphor and/or silicone droplets after dispensation may reduce oreliminate phosphor settling, thus improving the predictability andconsistency of the phosphor profile and thereby reducing variability inthe end product.

In block 250, power may be applied to the light emitting device 150,e.g., the LED. For example, a direct-current voltage may be applied ontwo terminals to forward-bias an LED, resulting in a current through theLED and the emission of light. The power may be a pulsed power, forexample, where the applied voltage takes the form of a square-wave.Here, the light emitted from the LED flickers according to theamplitude, phase, pulse width, frequency, and duty cycle of the pulsedpower. In embodiments including a pulsed power supply, the currentdriven through the LED may be reduced in comparison to a DC current, andheating of the LED is concomitantly reduced.

In block 260, light emitted from the light emitting device 150 may bedetected. For example, in some embodiments a sensor 130 senses the lightand communicates at least one characteristic of the light to thecontroller 110. The sensor 130 may be in close proximity to the lightemitting device or devices, or the sensor may not be in the immediateproximity, and a light guide, for example, one or more fiber lightguides may be utilized to guide light from the light emitting device ordevices 150 to the sensor 130. As discussed above, the at least onecharacteristic of the light may include a correlated color temperatureand/or a set of coordinates in a color space.

In block 270, the process may determine whether the at least onecharacteristic of the light detected in block 260 is at or near thetarget characteristic set in step 210. That is, the controller 110 mayperform a comparison between the detected characteristic determined bythe sensor 130 and the target characteristic entered into the controller110. The comparison may be performed with a hardware comparator, adifference amplifier, or software. Further, the target utilized for thecomparison may include a hard threshold, or the comparison may beweighted depending on a number of factors, including but not limited tothe amount of the phosphor composition already dispensed.

If the detected characteristic compares unfavorably to the targetcharacteristic, that is, if the light is off target, or the differencebetween the detected characteristic and the target characteristic isgreater than a predetermined threshold, the process may branch to block280. However, if the detected characteristic compares favorably to thetarget characteristic, that is, the light is on target, or thedifference between the detected characteristic and the targetcharacteristic is less than a predetermined threshold, the process maybranch to block 290.

In block 280, the process may adjust the dispense ratio. For example,the controller 110 may send an instruction to the dispenser 120 toadjust the relative amounts of concentrated colored phosphor suspensionand/or transparent silicone in order to “move” the characteristics ofthe light emitted from the light emitting device “closer” to the targetcharacteristics.

For example, FIG. 3 is an illustration of the International Commissionon Illumination (CIE) 1931 color space, known to those skilled in theart. This color space is a plot of the entire gamut of human-perceivablecolors according to a set of coordinates, that is, CIE x and CIE ycoordinates. Line 320 shows the color coordinates of a black bodyradiator at the labeled temperature (i.e., a color temperature). In anexemplary embodiment, a target characteristic of the light is acorrelated color temperature of approximately 3100K, or in anotherembodiment, a set of coordinates of CIE x=0.4±0.001, CIE y=0.4±0.001. Asan example, assume that at block 260, a detected light included a set ofcoordinates of CIE x=0.2, CIE y=0.1. At block 270, the processdetermines that the detected light is off target, so the processbranches to block 280, and the dispense ratio is adjusted. That is, therelative amounts of red, green, and yellow phosphors, and transparentsilicone, are adjusted in order to move the color coordinates towardsthe target coordinates.

In an exemplary embodiment, an adjustment of the dispense ratio may makeadjustments according to the position of the detected characteristic inrelation to the color temperature line 320. For example, if the detectedcharacteristic is below the color temperature line 320, the adjustmentmay include increasing the proportion of green phosphor. If the detectedcharacteristic is above the color temperature line 320, the adjustmentmay include increasing the proportion of the red phosphor. Similarly,increasing the proportion of the yellow phosphor may move the lightcharacteristic along the color temperature line in the direction ofdecreasing color temperature.

If the process determines that the light is sufficiently on target atblock 270, the process may branch to block 290. In block 290, theprocess may determine whether the total amount of the phosphorcomposition dispensed onto the light emitting device meets or exceedsthe target amount set in block 230. In various embodiments, thisdetermination may be made by the controller 110, the dispenser 120, oranother apparatus coupled to the light emitting device 150. Note thatvarious embodiments may make decisions based on the dispensed amountbeing equal to (=), greater than (>), or greater than or equal to (≧)the target amount, or based on some other suitable relationship betweenthe dispensed amount and the target amount. If the target amount hasbeen reached, the process may end. Otherwise, the process may branch toblock 240 for another iteration including dispensation of the phosphor,measurement of the characteristic of the light, and potentially,adjustment of the dispense ratio.

Those skilled in the art will comprehend the process illustrated in FIG.2 is only one example of a process within the scope of this disclosure,and variations and modifications may be made without departing from theintended scope. For example, another process may add another step ofdetermining whether the total amount of phosphor compound meets and/orexceeds the target amount after block 280, or at any other intermediatestep within the process.

Further, the described order or sequence of steps is not necessarily theonly possible implementation. For example, in some aspects theapplication of power to the light emitting device, and the detection ofthe characteristic of the light, are continuously performed concurrentlywith the dispensation of the phosphor compound onto the light emittingdevice. In certain aspects the application of power and detection of thecharacteristic of the light are not done continuously, nor are they donein any particular sequence, but they are done periodically, e.g., fromevery 100 ms to every 1 min., while the phosphor compound is dispensedonto the light emitting device, but independent of the timing of otherprocess steps.

By utilizing the process according to the above description, thecharacteristics of the light emitted by the phosphor-coated lightemitting device can be more precisely controlled, insuring that thecolor points or other characteristics of light emitted by a large numberof devices will have low variability, thus reducing or eliminating theneed for binning and improving production yield. Further, the necessityfor pre-mixing the phosphor composition is reduced or eliminated,reducing the costs of production.

In the foregoing specification, the invention has been described withreference to a number of exemplary embodiments. Various modificationsand changes may be made, however, without departing from the scope ofthe present invention as set forth in the claims and their equivalents.The specification and figures are illustrative, rather than restrictive,and modifications are intended to be included within the scope of thepresent invention. Accordingly, the scope of the invention should bedetermined by the claims and their legal equivalents rather than bymerely the examples described.

For example, the steps recited in any method or process claims may beexecuted in any order and are not limited to the specific orderpresented in the claims. Additionally, the components and/or elementsrecited in any apparatus claims may be assembled or otherwiseoperationally configured in a variety of permutations and areaccordingly not limited to the specific configuration recited in theclaims.

Benefits, other advantages and solutions to problems have been describedabove with regard to particular embodiments; however, any benefit,advantage, solution to a problem, or any element that may cause anyparticular benefit, advantage, or solution to occur or to become morepronounced are not to be construed as critical, required, or essentialfeatures or components of any or all the claims.

As used herein, the terms “comprise,” “comprises,” “comprising,”“having,” “including,” “includes” or any variation thereof, are intendedto reference a non-exclusive inclusion, such that a process, method,article, composition or apparatus that comprises a list of elements doesnot include only those elements recited, but may also include otherelements not expressly listed or inherent to such process, method,article, composition, or apparatus. Other combinations and/ormodifications of the above-described structures, arrangements,applications, proportions, elements, materials, or components used inthe practice of the present invention, in addition to those notspecifically recited, may be varied or otherwise particularly adapted tospecific environments, manufacturing specifications, design parameters,or other operating requirements without departing from the generalprinciples of the same.

The previous description is provided to enable any person skilled in theart to fully understand the full scope of the disclosure. Modificationsto the various configurations disclosed herein will be readily apparentto those skilled in the art. Thus, the claims are not intended to belimited to the various aspects of the disclosure described herein, butare to be accorded the full scope consistent with the language ofclaims, wherein reference to an element in the singular is not intendedto mean “one and only one” unless specifically so stated, but rather“one or more.” Unless specifically stated otherwise, the term “some”refers to one or more. A claim that recites at least one of acombination of elements (e.g., “at least one of A, B, or C”) refers toone or more of the recited elements (e.g., A, or B, or C, or anycombination thereof). All structural and functional equivalents to theelements of the various aspects described throughout this disclosurethat are known or later come to be known to those of ordinary skill inthe art are expressly incorporated herein by reference and are intendedto be encompassed by the claims. Moreover, nothing disclosed herein isintended to be dedicated to the public regardless of whether suchdisclosure is explicitly recited in the claims. No claim element is tobe construed under the provisions of 35 U.S.C.§112, sixth paragraph,unless the element is expressly recited using the phrase “means for” or,in the case of a method claim, the element is recited using the phrase“step for.”

1. A method of dispensing a phosphor composition onto a light emittingdevice, comprising: dispensing a portion of the phosphor compositiononto the light emitting device; detecting a characteristic of lightemitted by the light emitting device; and adjusting relative amounts ofrespective portions of the phosphor composition to reduce a differencebetween the detected characteristic of the light and a desiredcharacteristic of the light.
 2. The method of claim 1, wherein thedesired characteristic of the light comprises at least one of acorrelated color temperature (CCT) or a set of coordinates in a colorspace.
 3. The method of claim 2, wherein the desired characteristic ofthe light comprises the CCT and the set of coordinates in the colorspace.
 4. The method of claim 1, wherein the respective portions of thephosphor composition comprise respective colors of phosphor suspended insilicone.
 5. The method of claim 4, wherein the dispensing of thephosphor composition comprises dispensing each respective one of thecolors of phosphor utilizing a respective one of a plurality ofdispensers. 6-9. (canceled)
 10. The method of claim 4, wherein therespective portions of the phosphor composition further comprise asubstantially pure silicone. 11-13. (canceled)
 14. The method of claim1, further comprising applying a power to the light emitting device toemit light.
 15. The method of claim 14, wherein the power applied to thelight emitting device is adapted for testing the light emitting deviceat a pulsed condition.
 16. An apparatus operable in alight-emitting-device-manufacturing system, the apparatus comprising:means for dispensing the phosphor composition onto the light emittingdevice; means for detecting a characteristic of light emitted by thelight emitting device; and means for adjusting relative amounts ofrespective portions of the phosphor composition to reduce a differencebetween the detected characteristic of the light and a desiredcharacteristic of the light.
 17. The apparatus of claim 16, wherein thedesired characteristic of the light comprises at least one of acorrelated color temperature (CCT) or a set of coordinates in a colorspace.
 18. The apparatus of claim 17, wherein the desired characteristicof the light comprises the CCT and the set of coordinates in the colorspace.
 19. The apparatus of claim 16, wherein the respective portions ofthe phosphor composition comprise respective colors of phosphorsuspended in silicone.
 20. The apparatus of claim 19, wherein the meansfor dispensing the phosphor composition comprises means for dispensingeach respective one of the colors of phosphor utilizing a respectivemeans for dispensing a respective color phosphor. 21-24. (canceled) 25.The apparatus of claim 19, wherein the respective portions of thephosphor composition further comprise a substantially pure silicone.26-28. (canceled)
 29. The apparatus of claim 16, further comprisingmeans for applying a power to the light emitting device to emit light.30. The apparatus of claim 29, wherein the means for applying the powerto the light emitting device is configured for testing light emittingdevices at pulsed condition.
 31. A system for dispensing a phosphorcomposition onto a light emitting device, comprising: a light sensor fordetecting a characteristic of light emitted from the light emittingdevice; and a plurality of phosphor dispensers, each for dispensing arespective color phosphor onto a surface of the light emitting device,wherein the phosphor dispensers are adapted to be controlled in responseto the detected characteristic of the light emitted from the lightemitting device.
 32. The system of claim 31, wherein the phosphordispensers are further configured to adjust a ratio of the respectivecolor phosphors to dynamically reduce a difference between the detectedcharacteristic of the light and a desired characteristic of the lightwhile dispensing the respective portions of the phosphor composition.33. The system of claim 32, wherein the phosphor dispensers are furtherconfigured to dynamically adjust a dispensing time and/or speed toreduce the difference between the detected characteristic of the lightand the desired characteristic of the light while dispensing therespective portions of the phosphor composition. 34-35. (canceled) 36.The system of claim 31, further comprising a silicone dispenser fordispensing substantially pure silicone onto the surface of the lightemitting device. 37-53. (canceled)